Conventional film keyboards are designed in such a way that they comprise an upper and a lower film with a spacing device, a so-called "spacer", placed between them, and wherein the films, which in the normal state are maintained at a distance from each other, are pressed together by the key tappet and thus make contact. In an alternative fashion it is also possible to use only a single film with strip conductors and fixed contacts, in which case the tappet works as a movable contact bridge.
With the first mentioned arrangement, the film combination is relatively expensive to manufacture. The disposition of switching contacts directly on the key tappet is also relatively expensive, as it requires separate restoring springs for the key tappets.